Assassin

iTrader: (3)

I see everybody having problems getting a good maf tune in because the computer wants the afr to be at 14.6(or stoich) right?.... in hptuners vcm editor engine> fuel controll> general fuel .... there the stoich afr box that has 14.62857 ... could you just change this to 13.0 (or whatever) and the computer would figure everything out to be at 13.0 afr??? may be a stupid question but just thought I would ask...

txhorns281

iTrader: (12)

You are absolutely right. It's much more complicated than you thought!

The reason stoich AFR is set at 14.628 is b/c for pump gas, at that AFR, emissions are chemically the least pollutant. Also, your O2s are very good at detecting and maintaing stoich AFR (14.7) but definitely not so good at any other AFR. Even if you did change it, you would severely hinder the PCM's ability to keep fueling consistent. But this concept has little to do with tuning out the MAF. Unless your tune is way way off, you will always be running at stoich AFR (assuming Closed Loop operation and assuming you are not at the limit of your PCM's ability to adjust fueling). When you see people talking about making power at 13.0, the PCM enters Power Enrichment mode. This is where a fuel multiplier sends a signal to your injectors to jet lotsa fuel in to richen up to get you to your derived optimal AFR as far as performance is concerned.

Tuning the MAF is more about determining and deriving correct airflow in order to calibrate your MAF sensor. This does have alot to do with the functionality of your EFI system though. When you command a certain AFR, you obviously would expect to have the motor produce it. But such is not the case from the stock Ls1 tune, or many other modified tunes. A good tune will utilize the EFI system as what is was intended for. To command AFR and have the motor produce/maintain it without any extreme compensation factors having to be hard at work to correct for inconsistencies.

Assassin

iTrader: (3)

thanks... I've got another question you may be able to answer..... say you ditch the maf and turn off the ltft's, would ve table be reading at where the 100kpa map is or somewhere else, or do I have something confused... (useing wideband)

txhorns281

iTrader: (12)

I think you are definitely confused... j/k

if you go SD, and turn off trims, you'll basically be running comepletely off your VE table (Open loop). Betta make sure it's tuned correctly though, cuz if not, your AFR production will suck big ****** and there will also not be anything to adjust it for you... Your motor operation will remain the same as far as MAP and rpms and such. Just your fueling will be on complete manual control (That's you!).

Assassin

iTrader: (3)

I need to figure this out cause a friend of mine is getting boosted and needs tuned, how would you go about getting the comp to read a 3bar map censor?

Assassin

iTrader: (3)

I've been doing as much research as possible in 2 days and I'm probably getting the initials confused, I'll ask questions on a clear mind later on unless you have anything to add, thanks....

txhorns281

iTrader: (12)

Get a 3bar program

Assassin

iTrader: (3)

just a 3bar hptuners program or do you need to do something w/ the pcm?

Assassin

iTrader: (3)

2000Firehawk

iTrader: (248)

WAIT A MINUTE...

You can run SD on the VE tables with LTFTs off, CLOSED LOOP...

Thats the way I'm running now, it's so sweet....

Once your VE table has been dialed in, closed loop with STFT
will be giving you STOICH....

No MAF or LTFTs to muck things up....

Dave

Assassin

iTrader: (3)

I mean 2 bar...

Assassin

iTrader: (3)

so do you just turn pe to 110% throttle wich you will never get to?

Assassin

iTrader: (3)

you know what.. I'm totally confused and tired, could you give me a quick rundown.... thanks...

txhorns281

iTrader: (12)

with LTFTs off, it's almost like open loop. You will get a small bit of auto adjustment, but day to day your STFTs will jump around for sure and may put you in a place you don't wanna be. Having extreme STFTs isn't a good thing either. It's your LTFTs that help anchor/maintain stoich.

txhorns281

iTrader: (12)

huh

2000Firehawk

iTrader: (248)

Shes running fine...

My STFTs do jump around from one day to the next.
Thats job 1 for them....

There are others with LTFTs turned off, no problems...

STFT is an instantaneous adjustment & works most excellent...
Throttle Response is the way it should be, instantaneous....
I'm really really hooked on the super Throttle Response without
LTFTs...

LTFTs are super, & needed for a big big basket of things.
Like for so so VE table, mods without changing VE table, engine wear
over time, ect.

LTFT = for course tuned engine.
STFT = for fine tuned engine.

If it starts tuning ugly, I will turn LTFTs back on....

STFT rules, for now.......

Dave